1. Field of the Invention
The present invention relates to a spectroscopic system and methods for the identification and characterization of particles in a fluid, and, more particularly, to such systems and methods for the identification and characterization of particles in a bodily fluid.
2. Description of Related Art
A critical limitation in the area of disease identification, diagnosis, and prevention has been the lack of simple, rapid, and effective screening techniques. This problem is particularly acute in locations and/or situations where rapid analysis and diagnosismay involve decisions concerning life-threatening circumstances such as natural disasters or combat, and where the need for portable laboratories is accentuated by the remoteness of areas where diseases are endemic and where epidemics are generated. In addition, in the medical field there is a considerable need for the identification of markers that permit the diagnosis and treatment of diseases early in their development stage and thus avoid lengthy periods of incubation, which invariably worsen the condition of the patient.
Typically, microorganisms and viruses of concern have sizes ranging between 0.5 and 20 xcexcpm and, in many cases, are present in fairly dilute concentrations. Although the analytical instrumentation used in medical and clinical laboratories has improved considerably over the past decade to the present, there are still no suitable techniques capable of detecting, classifying, and counting microorganisms in bodily fluids.
Technology known in the art requires that the presence of target microorganisms be detected using microscopy and/or immunoassay techniques. These require a significant amount of time, trained technicians, and well-equipped laboratory facilities.
The costs associated with current laboratory techniques for disease identification and diagnosis therefore further accentuate the need for the development of rapid screening methods.
Another limitation of the currently employed technology is a lack of on-line capability and continuous measurement capabilities for the characterization of blood and other fluid components, as well as a lack of portable instrumentation capable of detecting, counting, and classifying specific blood and other fluid components. The problem of portable instrumentation and suitable methods of analysis and diagnosis is particularly relevant to the medical industry, where the need for rapid analysis and diagnosis often involves life-threatening situations. Although the analytical instrumentation used in medical and clinical laboratories has improved considerably over the past decade, there are still no suitable techniques capable of detecting, classifying, and counting on-line critical cell populations and/or pathogens in blood and other bodily fluids.
Blood cell component counting technology known in the art uses, for example, red cell counts, platelet counts, and white cell counts as indicators of the state of disease. White blood cells can be difficult to count if they are present in small numbers. At present automated hematology analyzers that employ light scattering or impedance techniques are used, but these can introduce a high error rate when determining counts for low sample numbers. In cases of leukoreduced blood products with lower numbers of white blood cells, staining and microscopy or flow cytometry are typically used.
As is known from spectroscopy theory, a measure of the absorption of the attenuation of light through a solution or a suspension is the extinction coefficient, which also provides a measure of the turbidity and transmission properties of a sample. Spectra in the visible region of the electromagnetic spectrum reflect the presence of metal ions and large conjugated aromatic structures and double-bond systems. In the near-ultraviolet (uv) region small conjugated ring systems affect absorption properties. However, suspensions of very large particles are powerful scatterers of radiation, and in the case of cells and microorganisms, the light scattering effect can be sufficiently strong to overwhelm absorption effects. It is therefore known to use uv/vis spectroscopyto monitor purity, concentration, and reaction rates of such large particles and their suspending media.
Many attempts have been made to estimate the particle size distribution (PSD) and the chemical composition of suspended particles using optical spectral extinction (transmission) measurements. However, previously used techniques neglect the effects of the chemical composition and require that either the form of the P80 be known a prioii or that the shape of the PSD be assumed. One of the present inventors has applied standard regularization techniques to the solution of the transmission equation and has demonstrated correct PSDs of a large variety of polymer lathces, protein aggregates, silicon dioxide and alumina particles, and microorganisms.
It has also been known to use the complementary information available from simultaneous absorption and light scattering measurements at multiple angles for the characterization of the composition and molecular weight and shape of macromolecules and suspended particles (Garcia-Rubio, 1993; and U.S. Pat. No. 5,808,738, the disclosure of which is incorporated herein by reference).
Interferometric techniques are known in the art for cell classification (Cabib et at., U.S. Pat. Nos. 5,991,028 and 5,784,162) which use fluorescence microscopy with stained cells. Fluorescence and reflection spectroscopy can also be used to characterize a material by sensing a single wavelength (Lemelson, U.S. Pat. Nos. 5,995,866; 5,735,276; and 5,948,272), which can detect organisms in a bodily fluid. Electroluminescence may also be used to detect an analyte in a sample (Massey et at., U.S. Pat. No. 5,935,779). Cell counting may be accomplished by vibrationalspectroscopy (Zakim et al. U.S. Pat. No. 5,733,739). Infrared techniques can detect cellular abnormalities (Cohenford et al., U.S. Pat. Nos. 6,146,897 and 5,976,885; Sodickson et al., U.S. Pat. No. 6,028,311).
One of the present inventors previously developed ultraviolet-visible spectroscopic techniques for detecting and classifying microorganisms in water (Garcia Rubio, U.S. Pat. No. 5,616,457), for characterizing blood and blood types (Garcia Rublo, U.S. Pat. No. 5,589,932), and, as mentioned above, for characterizing particles with a multiangle-multiwavelength system (Garcia-Rubio et at., U.S. Pat. No. 5,808,738). The disclosures of these patents are incorporated herein by reference.
It is therefore an object of the present invention to provide a system and method for identifying and diagnosing an infectious disease.
It is a further object to provide such a system and method for identifying and diagnosing such an infectious disease in the bloodstream.
It is another object to provide such a system and method for identifying and diagnosing such an infectious disease in another bodily fluid.
It is an additional object to provide such a system and method for identifying and diagnosing a blood disease.
It is yet a further object to provide such a system and method for identifying and diagnosing a disease that affects the size, shape, and/or chemical composition of a particulate or other component in a bodily fluid.
It is yet another object to provide such a system and method that are operable in a remote location.
These and other objects are achieved by the present invention, a method for detecting a presence of and identifying an infectious disease or disorder in a mammalian blood sample. Herein the word disorder is intended in its broadest sense, that is, as any abnormality detectable over a known range of characteristics of the measured particulates or suspending medium.
The method comprises the steps of taking a multiwavelength spectroscopy measurement, typically a transmission spectrum of a test blood sample in at least a portion of the ultraviolet visible near-infrared range of the electromagnetic spectrum and comparing the spectrum with a standard blood sample spectrum known to be free from the infectious disease or disorder. From the comparison it is then determined whether the blood from the test sample contains the infectious disease or disorder, and an identity of the infectious disease or disorder is determined.
Spectroscopic and multiwavelength turbidimetry techniques provide a rapid, inexpensive, and convenient means for diagnosis. As a first embodiment, the comparison and determination steps may be performed visually, since the signatures of certain diseases and disorders are so strong; in another embodiment it has been found that the spectral deconvolution of the turbidimetric spectra can provide additional and more detailed qualitative and quantitative information. Both embodiments of the invention can rapidly and inexpensively achieve disease diagnosis in remote locations and at a natural disaster, epidemic, or combat site.
In a particular subembodiment, a change in a blood particle or other component caused by an infectious agent or disorder is detected spectroscopically. Such a change may comprise, for example, a shape change, such as occurs with sickle cell anemia, or a lysis, for example, of a red blood cell, which releases free hemoglobin and bilirubin into the blood plasma.
In another subembodiment the test sample may comprise another bodily fluid for detecting a presence of an infectious disease or disorder.
The method is based on multiwavelength spectroscopy measurements and the interpretation of the absorption and scattering properties of single particles from a plurality of populations and their suspending media. The spectroscopy measurements may comprise transmission, reflectance, and multiangle multiwavelength, using either polarized or unpolarized light, in the uvvisnear-infrared portions of the electromagnetic spectrum. Unlike microscopy measurements, the samples typically comprise cells in the range of 106 particles. The analytical method yields such information as, but not intended to be limited to, particle counts, compositional analysis, size, and shape of the particulates and the suspending media.
The invention is believed to provide a multiplicity of improvements over the prior art in achieving a rapid, inexpensive, and convenient means for characterization and detection of particulates in a bodily fluid, including characterization of such particulates as, but not intended to be limited to, cell shapes, blood antigens, microorganisms, and viruses. The rapidity and portability of the system of the invention permits its use in critical conditions such as epidemics and combat and also in remote and/or technology-disadvantaged locations.
The features that characterize the invention, both as to organization and method of operation, together with further objects and advantages thereof, will be better understood from the following description used in conjunction with the accompanying drawing. It is to be expressly understood that the drawing is for the purpose of illustration and description and is not intended as a definition of the limits of the invention. These and other objects attained, and advantages offered, by the present invention will become more fully apparent as the description that now follows is read in conjunction with the accompanying drawing.